Abstract

In cryptographic terminology, the message is called plaintext or cleartext. Encoding the contents of the message in such a way that hides the contents from outsiders is called encryption.

The encrypted message is called ciphertext. The process of retrieving the plaintext from the ciphertext is called decryption. Encryption and decryption usually make use of a key and the coding method is such that the decryption can be performed only by knowing the proper key.

The method of encryption and
decryption is called cipher. All modern algorithms base their security on the usage of a key, a message can be decrypted only if the key used for decryption matches the key used for encryption.

There are two classes of key-based algorithms, symmetric (or secret key) and asymmetric (or public key) algorithms. Some algorithms do not require a key. Generally cryptographic algorithms can be classified into three types